In recent years, particularly in regard to semiconductor devices, high speed operation and low power consumption operation are demanded as a result of further progress of micronization, and there is a demand for high-end technologies such as integration of functions called by the name of system LSI. Among such, regarding the lithography technology that becomes the key of the production of a pattern of a semiconductor device, it has been pointed out that there are limitations on the photolithographic method in view of the problem of exposure wavelength and the like occurring along the progress of micronization of a device pattern, and exposure apparatuses are extremely expensive.
As an alternative measure, a nanoimprint lithography (NIL) method using a fine concavo-convex pattern is attracting more attention. The nanoimprinting method suggested by Chou and others of Princeton University in 1995 is expected as a technology capable for forming a fine pattern having a high resolution of about 10 nm while the apparatus price, materials used and the like are inexpensive.
An imprinting method is a technology of pressing a template (also called a mold or a stamper) on which a nanometer-sized concavo-convex pattern has been formed in advance on the surface, on a transfer material such as a resin that has been formed by coating on the surface of a transfer-receiving substrate, so as to mechanically transform the substrate surface, thereby precisely transferring the concavo-convex pattern, and processing the transfer-receiving substrate using the imprint material having a pattern formed thereon as a resist mask. Once a template is produced, since a nanostructure can be repeatedly molded in a simple manner, a high throughput is obtained, and thus it is economically efficient. Also, since the technology is a nanoprocessing technology which produces hazardous waste materials to a less extent, in recent years, application of the technology is not limited to semiconductor devices, and application thereof in a variety of fields is in progress.
Regarding such an imprinting method, a thermal imprinting method of thermally transferring a concavo-convex pattern using a thermoplastic material; a photoimprinting method of transferring a concavo-convex pattern by ultraviolet radiation using a photocurable material; and the like are known. For the transfer material, a thermoplastic resin is used in the thermal imprinting method, and a photocurable resin or the like is used in the photoimprinting method. In the photoimprinting method, pattern transfer can be achieved at a low applied pressure at room temperature, so that heating/cooling cycles such as those employed in the thermal imprinting method are unnecessary, and dimensional changes in the template, or the resin caused by heat do not occur. Therefore, it is said that the photoimprinting method is excellent in view of resolution, the extent of alignment, productivity and the like. Hereinafter, in the present invention, a photoimprinting method is simply referred to as imprinting method.
The imprinting method has a problem that, as the processing process is repeated, generated nanometer-sized fine particles tend to adhere to the template or the like, and machining defects are increased. Thus, there has been suggested a microprocessing apparatus which sends clean air to the interior of an imprinting apparatus in order to create a satisfactory transfer environment inside the imprinting apparatus (see Patent Literature 1).
Furthermore, the imprinting method has a problem that a gas such as air penetrates between the template and the transfer-receiving layer, causing the occurrence of areas where the resin of the transfer material is not filled into the concavities of the pattern on the template, and transferability is deteriorated thereby. Thus, there have been suggested an imprinting system and an imprinting method, by which a first gas having a solubility in the transfer-receiving layer lower than that of air is supplied when a transfer-receiving layer is formed, and a second gas having a solubility in the transfer-receiving layer higher than that of air is supplied when the pattern is transferred, so as to eliminate areas where the resin is not filled in, and to enhance transferability (see Patent Literature 2).